Former MTA chairman Joe Lhota made it clear to construction executives yesterday that he’s running for mayor, emphasizing that his strong management skills at the transit agency were easily transferable to City Hall.

“I am not going to talk all that much about my future,” he told the annual meeting of the New York Building Congress at the Mandarin Oriental. “But I will tell you this — I would not have left the MTA, a job and a position that I loved, if I wasn’t going to run for mayor of New York.”

That was how he began a 15-minute speech.

He ended on the same note.

“If you agree that the MTA is in a better position today than it was a year ago, then imagine what I can do in my future with a much more complex organization,” Lhota teased, eliciting loud applause from a group obviously friendly to his candidacy.

Richard Anderson, the organization’s president, joked at the end of the speech: “Okay, who’s got a question for Mayor Lhota?”

But Lhota — who hasn’t officially declared — faces a potentially bruising primary fight before he can become the Republican Party nominee.

Supermarket mogul John Catsimatides told The Post that he’s putting up $1 million of his own money to launch a mayoral bid on the GOP line. And Doe Fund founder George McDonald, who isn’t in the same billionaire league, nevertheless reported taking in $277,378. Former Bronx Borough President Adolfo Carrion is also trying to get into the GOP race, which also includes publisher Tom Allon.

One construction industry executive said Lhota would have to raise about $30 million to have a reasonable chance of becoming mayor in this overwhelmingly Democratic city. And that’s without expending large sums in a GOP showdown.

While he wouldn’t discuss mayoral politics before becoming a full-fledged candidate, Lhota offered glimpses of his possible campaign platform and governing style.

“It wasn’t magic,” he said in explaining how the MTA restored the subways just 36 hours after super-storm Sandy. “It was first-rate planning, excellent preparation and absolutely great implementation.”

Lhota pointed out that it took New Jersey Transit until yesterday to restore full service. And he took a jab at Con Ed for not moving faster to re-power the subways.

When that drew murmurs from the audience, Lhota responded characteristically with candor.

“I’m going to hit them up for contributions, so I’ll apologize later,” he said.

Lhota credited not only his management team for the MTA’s quick recovery after the storm, but also the union workers who “did a heroic job.”

City Councilman Robert Jackson (D-Manhattan), a progressive Democrat who attended the event, left sounding impressed.

“I thought he spoke very well as far as the leadership of the MTA,” said Jackson. “He spoke about teamwork, working together, preparations and he gave a big shout-out to the TWU and the unions.”

Usually, it’s Democrats who extoll the virtues of union workers, not Republicans.

But Lhota didn’t forget where his votes are.

He questioned the new $15 cash toll on the Verrazano Narrows Bridge to Staten Island, the city’s most Republican borough, even though it was the MTA that imposed it.